Pediatric astrocytomas are the most common form of brain cancer in children. This POI is designed to improve our understanding ofthe pathways that regulate these tumor cells and the environment in which such cells reside, and thereby to develop new therapeutic approaches. The Innovative Neuropathology (INP) Core seeks to facilitate this research through the following specific aims: 1. To generate and characterize primary pediatric astrocytoma cell lines and tissue resources. 2. To provide expert neuropathologic and molecular pathologic analysis of human and mouse astrocytoma models. 3. To develop innovative technologies for cellular and molecular characterization of pediatric astrocytomas and cell lines. 4. To ensure that tumor samples are used and analyzed in a statistically rigorous and efficient fashion. Given that the research of each project is heavily based upon the in vivo biology of human and mouse astrocytomas, the INP Core services focus on development and delivery of in vivo technologies such as immunohistochemistry, in situ hybridization, fluorescent in situ hybridization (FISH) for genomic aberrations, and genome wide technologies for studies in human tumors. In addition, the INP Core will work to improve emerging tissue technologies to enable analysis of small tumor samples and so conserve these rare tissue resources. In time these innovations can lead to clinical tests that identify patients who might benefit from particular targeted therapies (e.g. BRAF expression signatures that allow rapid screening for tumor samples likely to have BRAF mutations). The centralized nature ofthe INP Core will foster intellectual resource sharing and allow investigators to accurately compare and interpret their findings within the spectrum of research performed across all the projects. The INP Core has the requisite neuropathologic expertise, biostatistical knowledge, sophisticated resources, and experienced staff to carry out these aims and ensure that the POI meets its overall goals to improve our understanding of pediatric astrocytomas.